San Diego. San Diego is a popular fall travel destination with average temperatures in the low to mid 70s. This oceanside city offers some of California's best year-round weather as it hardly gets any rain except for a few days between late November and February.
Given two parallel lines and a transversal, alternate interior angles are congruent. The key here is that you are told the two lines are parallel, and you have learned that the relationships between the angles created by the intersection of the transversal line and the two parallel lines. All of the above are true based on the two lines being parallel with a transversal line intersecting.
The third line that intersects the two lines is called the transversal. Co-interior angles always lie on the same side of the transversal, never on opposite sides. The sum of a pair of co-interior angles is always equal to 180 degrees if the two lines are parallel to each other. When the two lines are not parallel, the sum of the two co-interior angles would not be exactly 180 degrees. This is an important axiom in geometry.